/**   
 * @class Ext.tree.TreeCheckNodeUI   
 * @extends Ext.tree.TreeNodeUI   
 *    
 * 对 Ext.tree.TreeNodeUI 进行checkbox功能的扩展,后台返回的结点信息不用非要包含checked属性   
 *    
 * 扩展的功能点有：   
 * 一、支持只对树的叶子进行选择   
 *    只有当返回的树结点属性leaf = true 时，结点才有checkbox可选   
 *    使用时，只需在声明树时，加上属性 onlyLeafCheckable: true 既可，默认是false   
 *    
 * 二、支持对树的单选   
 *    只允许选择一个结点   
 *    使用时，只需在声明树时，加上属性 checkModel: "single" 既可   
 *    
 * 二、支持对树的级联多选    
 *    当选择结点时，自动选择该结点下的所有子结点，以及该结点的所有父结点（根结点除外），特别是支持异步，当子结点还没显示时，会从后台取得子结点，然后将其选中/取消选中   
 *    使用时，只需在声明树时，加上属性 checkModel: "cascade" 既可   
 *    
 * 三、添加"check"事件   
 *    该事件会在树结点的checkbox发生改变时触发   
 *    使用时，只需给树注册事件,如：   
 *    tree.on("check",function(node,checked){...});   
 *    
 * 默认情况下，checkModel为'multiple'，也就是多选，onlyLeafCheckable为false，所有结点都可选   
 *    
 * 使用方法：在loader里加上 baseAttrs:{uiProvider:Ext.tree.TreeCheckNodeUI} 既可.   
 * 例如：   
 *   var tree = new Ext.tree.TreePanel({   
 *      el:'tree-ct',   
 *      width:568,   
 *      height:300,   
 *      checkModel: 'cascade',   //对树的级联多选   
 *      onlyLeafCheckable: false,//对树所有结点都可选   
 *      animate: false,   
 *      rootVisible: false,   
 *      autoScroll:true,   
 *      loader: new Ext.tree.DWRTreeLoader({   
 *          dwrCall:Tmplt.getTmpltTree,   
 *          baseAttrs: { uiProvider: Ext.tree.TreeCheckNodeUI } //添加 uiProvider 属性   
 *      }),   
 *      root: new Ext.tree.AsyncTreeNode({ id:'0' })   
 *  });   
 *  tree.on("check",function(node,checked){alert(node.text+" = "+checked)}); //注册"check"事件   
 *  tree.render();   
 *    
 */   
   
Ext.tree.TreeCheckNodeUI = function() {    
    //'multiple':多选; 'single':单选; 'cascade':级联多选    
    this.checkModel = 'multiple';    
        
    //only leaf can checked    
    this.onlyLeafCheckable = false;    
        
    Ext.tree.TreeCheckNodeUI.superclass.constructor.apply(this, arguments);    
};    
   
Ext.extend(Ext.tree.TreeCheckNodeUI, Ext.tree.TreeNodeUI, {    
   
    renderElements : function(n, a, targetNode, bulkRender){    
        var tree = n.getOwnerTree();    
        this.checkModel = tree.checkModel || this.checkModel;    
        this.onlyLeafCheckable = tree.onlyLeafCheckable || false;    
            
        // add some indent caching, this helps performance when rendering a large tree    
        this.indentMarkup = n.parentNode ? n.parentNode.ui.getChildIndent() : '';    
   
    var cb = (!this.onlyLeafCheckable || a.leaf);    
        var href = a.href ? a.href : Ext.isGecko ? "" : "#";    
        var buf = ['<li class="x-tree-node"><div ext:tree-node-id="',n.id,'" class="x-tree-node-el x-tree-node-leaf x-unselectable ', a.cls,'" unselectable="on">',    
            '<span class="x-tree-node-indent">',this.indentMarkup,"</span>",    
            '<img src="', this.emptyIcon, '" mce_src="', this.emptyIcon, '" class="x-tree-ec-icon x-tree-elbow" />',    
            '<img src="', a.icon || this.emptyIcon, '" mce_src="', a.icon || this.emptyIcon, '" class="x-tree-node-icon',(a.icon ? " x-tree-node-inline-icon" : ""),(a.iconCls ? " "+a.iconCls : ""),'" unselectable="on" />',    
            cb ? ('<input class="x-tree-node-cb" type="checkbox" ' + (a.checked ? 'checked="checked" />' : '/>')) : '',    
            '<a hidefocus="on" class="x-tree-node-anchor" href="',href,'" mce_href="',href,'" tabIndex="1" ',    
             a.hrefTarget ? ' target="'+a.hrefTarget+'"' : "", '><span unselectable="on">',n.text,"</span></a></div>",    
            '<ul class="x-tree-node-ct" style="display:none;" mce_style="display:none;"></ul>',    
            "</li>"].join('');    
   
        var nel;    
        if(bulkRender !== true && n.nextSibling && (nel = n.nextSibling.ui.getEl())){    
            this.wrap = Ext.DomHelper.insertHtml("beforeBegin", nel, buf);    
        }else{    
            this.wrap = Ext.DomHelper.insertHtml("beforeEnd", targetNode, buf);    
        }    
            
        this.elNode = this.wrap.childNodes[0];    
        this.ctNode = this.wrap.childNodes[1];    
        var cs = this.elNode.childNodes;    
        this.indentNode = cs[0];    
        this.ecNode = cs[1];    
        this.iconNode = cs[2];    
        var index = 3;    
        if(cb){    
            this.checkbox = cs[3];    
            Ext.fly(this.checkbox).on('click', this.check.createDelegate(this,[null]));    
            index++;    
        }    
        this.anchor = cs[index];    
        this.textNode = cs[index].firstChild;    
    },    
        
    // private    
    check : function(checked){    
        var n = this.node;    
        var tree = n.getOwnerTree();    
        this.checkModel = tree.checkModel || this.checkModel;    
            
        if( checked === null ) {    
            checked = this.checkbox.checked;    
        } else {    
            this.checkbox.checked = checked;    
        }    
            
        n.attributes.checked = checked;    
        tree.fireEvent('check', n, checked);    
            
        if(!this.onlyLeafCheckable && this.checkModel == 'cascade'){    
            var parentNode = n.parentNode;    
            if(parentNode !== null) {    
                this.parentCheck(parentNode,checked);    
            }    
            if( !n.expanded && !n.childrenRendered ) {    
                n.expand(false,false,this.childCheck);    
            }    
            else {    
                this.childCheck(n);    
            }    
        }else if(this.checkModel == 'single'){    
            var checkedNodes = tree.getChecked();    
            for(var i=0;i<checkedNodes.length;i++){    
                var node = checkedNodes[i];    
                if(node.id != n.id){    
                    node.getUI().checkbox.checked = false;    
                    node.attributes.checked = false;    
                    tree.fireEvent('check', node, false);    
                }    
            }    
        }    
            
    },    
        
    // private    
    childCheck : function(node){    
        var a = node.attributes;    
        if(!a.leaf) {    
            var cs = node.childNodes;    
            var csui;    
            for(var i = 0; i < cs.length; i++) {    
                csui = cs[i].getUI();    
                if(csui.checkbox.checked ^ a.checked)    
                    csui.check(a.checked);    
            }    
        }    
    },    
        
    // private    
    parentCheck : function(node ,checked){    
        var checkbox = node.getUI().checkbox;    
        if(typeof checkbox == 'undefined')return ;    
        if(!(checked ^ checkbox.checked))return;    
        if(!checked && this.childHasChecked(node))return;    
        checkbox.checked = checked;    
        node.attributes.checked = checked;    
        node.getOwnerTree().fireEvent('check', node, checked);    
            
        var parentNode = node.parentNode;    
        if( parentNode !== null){    
            this.parentCheck(parentNode,checked);    
        }    
    },    
        
    // private    
    childHasChecked : function(node){    
        var childNodes = node.childNodes;    
        if(childNodes || childNodes.length>0){    
            for(var i=0;i<childNodes.length;i++){    
                if(childNodes[i].getUI().checkbox.checked)    
                    return true;    
            }    
        }    
        return false;    
    },    
        
    toggleCheck : function(value){    
        var cb = this.checkbox;    
        if(cb){    
            var checked = (value === undefined ? !cb.checked : value);    
            this.check(checked);    
        }    
    }    
});  